Beavers Could Be a Small Climate-Change Weapon

Could beavers be a small but potent weapon in our fight against climate change? A new international study of a Swiss stream where beavers have been active since 2010 suggests that may be the case. Researchers found that beavers' dam-building turns wetlands into surprisingly strong carbon sinks, locking away carbon at up to 10 times the rate of similar beaver-free sites. LiveScience shares the math: The studied wetland was a net sink that sequestered 108 to 146 tons of carbon annually—an "amount of carbon saved [that] is equivalent to 832 to 1,129 barrels of oil consumed."

By "slowing water, trapping sediment, and expanding wetlands," the animals "fundamentally shift how CO2 moves" through the landscape, says Joshua Larsen, lead author of the study published in Communications Earth & Environment. Researchers found sediments in beaver wetlands held up to 14 times more inorganic carbon than nearby forest soils, with deadwood from adjacent forests accounting for nearly half of long-term storage.

That long-term part is notable: The researchers point out the carbon reserves created by the beavers can hold for decades, making "beaver-modified wetlands ... stable, long-term carbon sinks as long as the dams remain intact," per a University of Birmingham press release. If beavers recolonized all suitable Swiss floodplains, the team estimates their wetlands could offset 1.2% to 1.8% of the country's yearly emissions. "Notably, this benefit would come without direct human intervention or additional cost," adds the release.

CREAF, which was involved in the study, notes the European beaver was nearly wiped out in the 19th century due to hunting, but has been reintroduced in recent decades. "Initially, there was a perception that it was an invasive species," per CREAF, which clarifies that the European beaver feeds largely on small grasses and shrubs within 60 feet of the riverbed, and typically builds smaller dams in secondary or tertiary tributaries. "With the American beaver we do see images in Patagonia with thousands of hectares of dead trees because it is not native; this would not happen with the European beaver," says study co-author Josep Barba.